In heat exchangers used for refrigerant applications the lines carrying refrigerant are typically embodied as flat tubes. The latter on the side of the longitudinal ends are in each case accommodated in a collector tube or a collector, respectively. Additional cooling requirements are created here particularly in the field of hybrid or electric vehicles, for example for cooling a vehicle battery, whereby a battery cooler of this type in the context of the changeover to the R744-type (CO2) refrigerant has be to re-designed on account of the higher system pressures and the simultaneously lower mass flow rates. In order to be able to ensure sufficient resistance to pressure also in the long term, the concepts which have been carried over from evaporators/condensers have to be downsized to smaller cross sections.
Furthermore, integral collector solutions exist for refrigerants based on fluorocarbon. Said integral collector solutions are based on concepts which are usual in condensers, whereby adapting the concepts which have been carried over from evaporators/condensers to integral collectors having a significantly smaller cross section requires extremely complex punching solutions, since internal bracing can be implemented only with difficulty. Passages cannot be fitted in the case of an internal matrix, since the internal diameter is too small. In the case of a two-part collector solution, the passages of the R134A-type condenser solution to date cannot be produced at the required smaller diameters and simultaneously larger wall thicknesses, this being particularly disadvantageous since these passages serve as introduction ramps for the flat tubes and moreover improve the capability of the individual parts for coffering. Moreover, problems in terms of strength and joining of the collector are to be expected.